X-ray sources using linear accumulation

Patent metadata

Field	Value
Publication number	US-9543109-B2
Application number	US-201614999147-A
Country	US
Kind code	B2
Filing date	Apr 1, 2016
Priority date	Sep 19, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A compact source for high brightness x-ray generation is disclosed. The higher brightness is achieved through electron beam bombardment of multiple regions aligned with each other to achieve a linear accumulation of x-rays. This may be achieved by aligning discrete x-ray sub-sources, or through the use of x-ray targets that comprise microstructures of x-ray generating materials fabricated in close thermal contact with a substrate with high thermal conductivity. This allows heat to be more efficiently drawn out of the x-ray generating material, and in turn allows bombardment of the x-ray generating material with higher electron density and/or higher energy electrons, leading to greater x-ray brightness. The orientation of the microstructures allows the use of an on-axis collection angle, allowing the accumulation of x-rays from several microstructures to be aligned to appear to have a single origin, also known as “zero-angle” x-ray radiation.

First claim

We claim:

1. An x-ray source comprising:
a vacuum chamber;
a window transparent to x-rays attached to the wall of the vacuum chamber;
and, within the vacuum chamber,
at least one electron beam emitter; and
an anode target comprising:
a substrate comprising a first selected material, and
a planar first surface, from which thickness is measured in a direction perpendicular to the first planar surface, and
two orthogonal lateral dimensions are measured parallel to the first planar surface; and

a plurality of discrete structures embedded into the first planar surface of the substrate such that each of the plurality of discrete structures is in thermal contact with the substrate,
the plurality of discrete structures comprising a second material selected for its x-ray generation properties;

in which at least two of the plurality of discrete structures are arranged on an axis;
in which the axis is parallel to the first planar surface of the substrate;
in which the axis passes through the first window;
in which each of the discrete structures has a thickness of less than 20 microns, in which each of the plurality of discrete structures has a lateral dimension in the direction of the axis of less than 50 microns; and

a means for directing an electron beam emitted by the at least one electron beam emitter onto the at least two arranged discrete structures such that x-rays are generated from each of the at least two arranged discrete structures;
in which at least a portion of the generated x-rays propagating on the axis from each of the two arranged discrete structures is transmitted through the window.

2. The x-ray source of claim 1 , in which any two of the plurality of discrete structures are separated by distance of 1 micron or greater.

3. The x-ray source of claim 1 , in which the plurality of discrete structures are buried into the surface of the substrate within a depth of less than 100 microns.

4. The x-ray source of claim 1 , in which the means for directing an electron beam emitted by the at least one electron beam emitter onto the at least two arranged discrete structures in the target comprises electron optics.

5. The x-ray source of claim 4 , in which the means for directing an electron beam allows for directing the electron beam in a pattern that corresponds to the positions of at least some the plurality of discrete structures, in which said pattern can be adapted in time in response to a signal from a detector monitoring predetermined properties of the x-rays generated by the directed electron beam, and in which said predetermined properties of the generated x-rays are selected from the group consisting of:
brightness, total intensity, flux, energy spectrum, beam profile, and beam divergence.

6. The x-ray source of claim 4 , in which the plurality of discrete structures of the target are aligned such that x-rays generated by a predetermined one of the plurality of discrete structures when exposed to an electron beam directed onto the at least two arranged discrete structures in the target are transmitted through another of the plurality of discrete structures.

7. The x-ray source of claim 6 , in which the target is aligned such that x-rays generated by a predetermined number of the plurality of discrete structures when exposed to the directed electron beam are transmitted through one predetermined discrete structure selected from the plurality of discrete structures.

8. The x-ray source of claim 1 , in which the plurality of discrete structures are arranged in a linear array.

9. The x-ray source of claim 8 , in which the linear array is defined to have a long axis and a short axis, and the long axis of the linear array is aligned with the window; and
the angle between the long axis and the surface normal of the window at the point of intersection between the long axis and the window is less than 85 degrees.

10. The x-ray source of claim 9 , in which at least one of the discrete structures is positioned to be within 500 microns of an edge of the substrate that is closest to the window.

11. The x-ray source of claim 1 , in which the plurality of discrete structures are fabricated to have similar shapes.

12. The x-ray source of claim 11 , in which the similar shapes are selected from the group consisting of regular prisms, right rectangular prisms, cubes, triangular prisms, trapezoidal prisms, pyramids, tetrahedra, cylinders, spheres, ovoids, and barrel-shapes.

13. The x-ray source of claim 1 , in which the first selected material is selected from the group consisting of:
beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.

14. The x-ray source of claim 1 , in which the second material is selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

15. The x-ray source of claim 1 , in which a subset of the plurality of discrete structures comprise a third material selected for its x-ray generation properties.

16. The x-ray source of claim 15 , in which the third material is selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

17. The x-ray source of claim 1 , in which at least one of the discrete structures is positioned to be within 500 microns of an edge of the substrate.

18. The x-ray source of claim 1 , additionally comprising:
a cooling system comprising:
a reservoir for storing a cooling fluid;
a channel within the substrate for conducting the cooling fluid;
an additional channel to conduct the fluid from the reservoir to the channel in the substrate;
an additional channel to conduct the fluid from the channel in the substrate to the reservoir; and
a pumping mechanism to pump the fluid through the system.

19. The x-ray source of claim 1 , additionally comprising:
a mechanism to rotate the target while being bombarded with electrons from said electron beam emitter.

20. The x-ray source of claim 1 , in which the plurality of discrete structures are aligned to produce a beam of x-rays with a take-off angle of less than 6° relative to said planar first surface.

Assignees

• Sigray Inc

Inventors

• Yun Wenbing
• Lewis Sylvia Jia Yun
• Kirz Janos
• Lyon Alan Francis

Classifications

• H01J2235/086

  Target geometry · CPC title

• H01J35/08

  Anodes; Anti cathodes · CPC title

• H01J35/106 Primary

  Active cooling, e.g. fluid flow, heat pipes · CPC title

• H01J35/18

  Windows · CPC title

• G21K1/06

  using diffraction, refraction or reflection, e.g. monochromators (G21K1/10, G21K7/00 take precedence) · CPC title